84 



IOWA ACADEMY OF SCIENCES. 



TABLE — CONTIKUED. 



Acer dasycarpum. 

 Medica{}osativa.. 



Russian Oak {Qucreus robur, var 

 pedunculata) 



Mongolian Pear {Pyrus sinensis) . 

 Prunus serotina 



Populus aJha 



Lutovlia (cherry) Prunus cerasus 



Rosa rugosa 



Prunus angustifolia 



Celtis occidentalis 



Prunus pumila 



Apricot (Nli'hol's) Prunus armeniaca. 



12 M (Pear) Piyn/N ci/iuiuni/N 



327 (Ax>p\e)Pynis iiHiUis 



75 M (Apple) Pynis mains 



Wythe (Apple) i'//r(/N im,his 



413 (Apple) Pi/n'N /(/((/"s 



15 M (Apple) Pi/ri/x iiinliis 



Fluke's wild Ura,l) ^Puriis loensis) .... 



Talman Sweet (Pyrus nialus) 



Rawle's Janet {Pyrus malus) 



Pyi~us toringo 



210,000 

 91,000 



315,000 

 82.500 



150,000 



55.000 

 253,500 

 33,000 

 90,000 

 88,0(10 

 197,000 

 150,000 

 167.500 

 155,000 

 220.000 

 170,000 



j L. .00088 

 I W. .00070 



J L. .00057 ) 



I W. .00044 r 



L. .00102 / 



W. .00070 f 



j L. .00119 ) 



I vv. .00091 r 



J L. .00177 I 



I W. .00135 f 



j L. .00115 / 



I W. .00075 f 



A KEY FOR THE IDENTIFICATION OF THE WEED SEEDS FOUND IN 

 C1.0VER SEED.i 



BY. T C. STEWABT. 



The identification of weed seeds, though an important matter, is not an easy 

 one. The average person knows Fox-tail, and probably that is about all. Even 

 botanists, who have not given the subject special attention, will be surprised to find 

 how small a number of weed seeds they are able to identify without study. 



Outside of systematic works' but little has been written on seed characters. 

 What has been written is scattered through Experiment Station Bulletins and 

 Agricultural Reports, and is not in an available form. However, the Germans 

 have done some good work in this line, notably Harz» and Nobbe.* 



A good key for the identification of American weed seeds would be of great 



iPart of a thesis on The Impurities of Clover Seed, written for the degree of 

 Bachelor of Science, Iowa Agricultural College. 



2 Gray's Manual of the Botany of the Northern U. 3., Chapman's Flora of the South- 

 ern States, Coulter's Rocky Mountain Botany, etc. 



Landwirtschaftliche Samenkunde, two volumes, Berlin 1885. Paul Parey. 

 Handbuch der Samenkunde, Berlin, Wilgandt, Hempel and Parey, 1876. ' 



